Implant

ABSTRACT

An implant includes a section made of polymer, wherein at least a portion of the section has a layer of a polymerizable and/or cross-linkable material. A method for fixation of a bone plate having several plate holes using the implant includes removing a cover sheet protecting the layer of polymerizable and/or cross-linkable material, activating the layer of polymerizable and/or cross-linkable material with electromagnetic energy or with moisture, introducing the implant into one of the plate holes of the bone plate when the bone plate is positioned on a bone, pressing on an end of the implant in order to contact the activated layer of polymerizable and/or cross-linkable material with the bone underneath the bone plate, and allowing the activated and pressurized layer of polymerizable and/or cross-linkable material to polymerize and/or cross-link and to adhere to the bone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/527,609, filed Aug. 25, 2011, and claims priority to U.S.Provisional Patent Application No. 61/609,913, filed Mar. 12, 2012, eachof which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention in some embodiments generally relates to animplant for attachment to bone. More particularly, the present inventionin some embodiments relates to an implant (e.g., a tack) for thefixation of a bone plate to a bone surface, the implant having one sidecoated with a bone adhesive or layer of a polymerizable and/orcross-linkable material that can be pressed through the opening of aplate onto the bone surface and provide a reliable adhesion strength.Some embodiments of the invention relate to an assembly comprising animplant according to the invention and a bone plate and to a method forfixation of a bone plate by means of an implant according to theinvention.

BACKGROUND OF THE INVENTION

Some typical bone fixation techniques like screw insertion offer theadvantage of reliability and speed but have drawbacks, among them arethe damages caused to bone by drilling and tapping and the possibilityof bone splitting following the screw insertion. In case of revision,the insertion of a rescue screw may be difficult or impossible.Moreover, for small, thin, bony structures, as can be found for examplein the midfacial area, screw insertion is often difficult because of thelimited available screw purchase.

Thus, there remains a need for an improved adhesive fixation techniqueavoiding the need for invasive insertion of a screw.

BRIEF SUMMARY OF THE INVENTION

The present invention in some embodiments relates to an implant forimplantation in a patient comprising a rear end for manipulating theimplant and a front end for contacting a bone surface, wherein the frontend comprises an uncured layer of a polymerizable and/or cross-linkablematerial.

Said polymerizable and/or cross-linkable material, in some embodiments,may include a thermoplast, thermoset, elastomer, duromer or a resorbablepolymer. In some embodiments, the polymerizable or cross-linkablematerial is nonresorbable. The layer of polymerizable or cross-linkablematerial can be applied to the implant, which may in a form of a rigidtack. In one such embodiment, the tack can include or be made of abiocompatible and biostable polymer, for example, polyether ether ketone(PEEK) or, in other embodiments, can be made of fully reactedpoly(methyl methacrylate) (PMMA). In some embodiments, the tack is madeat least partially or entirely from a nonresorbable material. In otherembodiments, the tack is made from a resorbable material. In someembodiments, both the tack and the layer of polymerizable and/orcross-linkable material are resorbable.

In some embodiments, the lower side of the tack can be coated with athin, well-controlled layer of the polymerizable and/or cross-linkablematerial, which can be activated with UV light or alternatively withmoisture. For example, in some embodiments, a well-controlled layer ofpolymerizable and/or cross-linkable material may have characteristicssuch as a defined thickness, defined chemistry, and homogeneity. In someembodiments, the layer of a polymerizable and/or cross-linkable materialcan be activated just before insertion by irradiation with visible or UVlight and then the tack can be pressed onto a surface, e.g., a bonesurface. In some embodiments, the tack can be inserted into an openingof a bone plate to secure the bone plate onto a bone surface. Thecombined effect of pressure with light will ensure a good activation ofthe layer of a polymerizable and/or cross-linkable material and a goodadhesion of the tack to the surface.

In some embodiments the implant comprises a section made of atransparent polymer adjacent to the front end. In some embodiments, thetransparent polymer section extends from the front end to the rear endof the implant. This configuration, in some embodiments, permits theadvantage that electromagnetic energy, e.g., visible or UV light can betransmitted from the rear end of the implant through the transparentsection to the layer of polymerizable and/or cross-linkable material toactivate said layer.

In a further embodiment of the implant said layer of polymerizableand/or cross-linkable material comprises a polymerizable amphiphilicmonomer. The surface characteristics of cortical bone and metallicimplants are dissimilar; therefore in some embodiments the chemistry ofthe adhesive layer should be compatible with two antagonist medias. Theuse of an amphiphilic layer of a polymerizable and/or cross-linkablematerial that is hydrophilic and hydrophobic simultaneously solves thisproblem according to some embodiments.

In some embodiments of the implant, said amphiphilic monomer comprises acomponent selected from the group of branched or linear, substituted orunsubstituted, saturated or partially unsaturated C₁₀-C₃₀ alkyl-,alkenyl-, alkylaryl-, aryl-, cycloalkyl-, alkylcycloalkyl-,alkylcykloaryl-carboxylates, -phosphates, or -sulfates or mixturesthereof.

In yet another embodiment of the implant said amphiphilic monomer is atleast one component selected from the group of the linear unsubstitutedC₁₀-C₂₀ alkyl-carboxylates or alkyl-sulfates, or their alkali- or earthalkali-salts, respectively, preferably laurate, stearate, palmitate,myristate, oleate, behanate, dodecylsulfate, preferably as alkali- orearth alkali-salts or mixtures thereof.

In another embodiment said implant is enclosed in a sterile pack. Insome embodiments, the sterile pack is configured to block exposure ofthe implant to radiation. In some embodiments, the sterile pack is madefrom a material opaque to visible and/or UV-light.

In a further embodiment of the implant, said polymerizable and/orcross-linkable material is a moisture-activated isocyanate leading to apolyurethane. Therewith an advantage can be achieved, according to someembodiments, in that the layer of a polymerizable and/or cross-linkablematerial can be activated with moisture.

In some embodiments of the implant, said implant is configured as atack, pin, screw or bolt with a front end and a rear end and whereinsaid layer of a polymerizable or cross-linkable material is attached tosaid front end.

In some embodiments where said implant is configured as a pin, the pincan be attached to and used for repositioning of a bone fragment. Insome embodiments, this configuration permits that a repositioninstrument or an internal or external fixator can be attached to thepins. In some embodiments of the implant, said pin has a length L ofminimum about 45 mm, preferably minimum about 50 mm. In still anotherembodiment of the implant said pin has a length L of maximum about 110mm, preferably maximum about 100 mm.

In a further embodiment of the implant said layer is protected by aremovable cover sheet, preferably a multi-layer cover sheet. Themulti-layer cover sheet may comprise e.g., a thicker paper layer and athinner anti-adhesion layer destined for direct contact with said layerof polymerizable and/or cross-linkable material.

In some embodiments of the implant, the implant includes a polymersection. In some embodiments, the polymer section extends from the rearend to the front end of the implant. In some embodiments of the implant,said polymer section is rigid. In some embodiments, said polymer sectionis transparent to visible light and/or UV irradiation. Thisconfiguration according to some embodiments permits an advantage thatthe implant, e.g., in the form of a tack for fixation of a bone plate,can be pressed through the bone plate opening as far as the lower sideof the tack comprising the layer of polymerizable and/or cross-linkablematerial contacts the bone surface and then the layer of a polymerizableand/or cross-linkable material can be activated with visible or UV lighttransmitted through the rigid tack that is transparent to visible or UVlight. In some embodiments of the implant, said polymer section is madeof a biocompatible and biostable polymer, preferably PEEK or PMMA.

In a further embodiment of the implant said layer of a polymerizableand/or cross-linkable material comprises a material chosen from thefollowing group: epoxy resins, fibrin adhesive, polyurethane. In afurther embodiment of the implant said polymerizable or cross-linkablematerial is a cyanoacrylate.

In another embodiment of the implant said layer of a polymerizableand/or cross-linkable material has a thickness of about 100 nm to about1000 μm, preferably of about 100 μm to about 500 μm.

In another embodiment said implant is a bone plate comprising said layerof a polymerizable or cross-linkable material at its lower side destinedto be contacted with bone.

In another embodiment said implant, preferably at its polymer sectioncomprises a suture.

In accordance with another aspect, an assembly is provided whichcomprises an implant according to the invention and a bone plate withseveral plate holes wherein said implant is a fixation element with arear side, one or more lateral sides and a front side for insertion intosaid plate holes. Further, said front side is provided with said layerof a polymerizable or cross-linkable material.

In one embodiment of the assembly, said lateral sides of said implantare provided at least partially with said layer of a polymerizable orcross-linkable material.

In a further embodiment of the assembly at least part of the surfaces ofsaid fixation element and of said plate holes comprise interlockingmeans, preferably in the form of hooks and eyelets. An advantage of thisconfiguration according to some embodiments is a better interlocking andfixation of the fixation elements in the plate holes.

According to a further aspect of the invention, there is provided amethod for fixation of a bone plate having several plate holes by meansof a longitudinal fixation implant with a front and rear end, comprisinga polymer section at its front end with a layer of a polymerizable orcross-linkable material protected by a removable cover sheet. The methodcomprising the following steps: a) removing said cover sheet; b)activating said polymerizable or cross-linkable material withelectromagnetic energy or with moisture; c) introducing saidlongitudinal fixation implant into one of said plate holes of said platepositioned on a bone; d) pressing on said rear end in order to contactsaid activated layer of said front end with the bone underneath saidbone plate: and e) allowing said activated and pressurized layer topolymerize or cross-link and to adhere to the bone.

In another embodiment of the method, said implant comprises a sectionmade of a transparent polymer adjacent to the front end of the implant;and wherein step c) is performed before step b) which particularlycomprises activating said polymerizable or cross-linkable material withelectromagnetic energy through said section made of a transparentpolymer.

In a further embodiment the method comprises the further step ofremoving the periosteum of said bone where said front end of saidlongitudinal fixation implant is to be pressed against said bone.

In accordance with another embodiment, there is a method forrepositioning bone fragments by means of one or more pins with a frontend, a rear end and an uncured layer of a polymerizable orcross-linkable material at said front end. The method includes the stepsof a) performing an incision each in the region of each bone fragment tobe reduced; b) removing said cover sheet from said pin; c) activatingsaid polymerizable or cross-linkable material with electromagneticenergy or with moisture; d) introducing said pin in the soft tissue; e)pressing on said rear end in order to contact said activated layer ofsaid front end with the respective bone fragment; f) allowing saidactivated and pressurized layer to polymerize or cross-link and toadhere to the bone; repeating steps b) to f) for each bone fragment tobe repositioned; and reducing the bone fracture by using said one ormore pins as a reduction aid.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the invention will be described in the followingby way of example and with reference to the accompanying drawings inwhich:

FIG. 1 illustrates a section through an implant according to oneembodiment of the invention in the form of a fixation element for a boneplate;

FIG. 2 illustrates a perspective view of another embodiment of theimplant according to one embodiment of the invention in the form of athreaded tack for a bone plate;

FIG. 3 illustrates another perspective view of the embodiment of theimplant according to FIG. 2;

FIG. 4 illustrates a perspective view of an embodiment of an assemblyaccording to one embodiment of the invention;

FIG. 5 illustrates a perspective view from distal of the embodiment ofthe assembly according to the embodiment of FIG. 4 used for fixation ofa base proximal phalanx fracture;

FIG. 6 illustrates a perspective view from proximal of the embodiment ofthe assembly according to the embodiment of FIG. 4 used for fixation ofa base proximal phalanx fracture;

FIG. 7 illustrates a sectional view of the embodiment of the assemblyaccording to the embodiment of FIG. 4 used for fixation of a baseproximal phalanx fracture;

FIG. 8 illustrates a perspective view of another embodiment of theassembly according to one embodiment of the invention;

FIG. 9 illustrates an elevational view of an assembly according to oneembodiment of the invention; and

FIG. 10 illustrates a further use of the implant according to anembodiment of the invention for repositioning bone fragments.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an embodiment of the implant 1 in the form of afixation element for a bone plate that is positioned over bone. In someembodiments, implant 1 may be configured as a tack, screw, bolt, or thelike. In some embodiments, implant 1 is substantially cylindrical inshape. In some embodiments, implant 1 (e.g., in the form of a tack)includes a cylindrical core having substantially constantcross-sectional dimension (e.g., diameter) along its length which may bethreaded or unthreaded. In other embodiments, as shown in FIG. 1, thetack may have a tapered or varying cross-sectional dimension (e.g.,diameter) along its length. In some embodiments, for example, implant 1may be in the form of a conical tack.

Implant 1, in some embodiments, has a longitudinal shape with alongitudinal axis 23, a rear end 19 and a front end 18. In someembodiments, implant 1, or at least a portion thereof (e.g., rear end19), is made from a substantially rigid material. According to oneembodiment, implant 1 is unthreaded. In some embodiments, implant 1 istapered from rear end 19 to front end 18 such that a cross-sectionaldimension (e.g., a diameter) of implant 1 at front end 18 is less thanthe cross-sectional dimension at rear end 19. In some embodiments frontend 18 is substantially flat. In other embodiments, front end 18 definesa concave surface. In some embodiments, front end 18 is contoured tosubstantially match the curvature of the bone surface to be contacted.In some embodiments, front end 18 is made from a compliant material thatcan bend to match the contour of the bone surface when pressed againstthe bone surface. In some embodiments, front end 18 is not configured topenetrate through the surface of a bone. In some embodiments, front end18 is not configured to penetrate further than the cortical layer of abone. In some embodiments, front end 18 is provided with an uncuredlayer 3 of a polymerizable and/or cross-linkable material which isconfigured to adhere or attach implant 1 to bone, as will be describedfurther herein. In some embodiments, layer 3 may be protected with aremovable coversheet 4 prior to implantation.

FIGS. 2 and 3 illustrate another embodiment of the implant 1. Theimplant 1 according to this embodiment is configured as a fixationelement 9 in the form of a threaded tack with a layer 3 of apolymerizable and/or cross-linkable material. The layer 3 is arranged atthe front side 11 of front end 18 of the fixation element 9 for contactwith the surface of a bone. In some embodiments, fixation element 9includes one or more lateral sides which may be provided at leastpartially with the layer 3 of a polymerizable and/or cross-linkablematerial. In some embodiments, layer 3 can be configured as describedwith regards to FIG. 1. Before the fixation element 9 is used the layer3 can be protected with a removable cover sheet as described withregards to FIG. 1. In some embodiments, rear end 19 of the threaded tackis configured to receive a tool for screwing or driving the threadedtack into a bone plate. In some embodiments, rear end 19 further definesa cavity for receiving the tool.

In some embodiments, implant 1 or at least a portion thereof is made ofa material transparent to visible and UV radiation and includes, at itsfront end 18, a layer 3 of a polymerizable and/or cross-linkablematerial. In some embodiments, implant 1 comprises at least a sectionmade of a transparent and preferably rigid material adjacent to frontend 18. This configuration permits the advantage that electromagneticenergy, e.g., visible or UV light can be transmitted from the throughthe transparent section to layer 3 of polymerizable and/orcross-linkable material to activate said material of layer 3 accordingto some embodiments. In some embodiments, the transparent section ismade from a transparent polymer. In some embodiments, the transparentsection is made from a transparent thermoplastic polymer. In someembodiments, the transparent section is made from polyether ether ketone(PEEK) or poly(methyl methacrylate) (PMMA). In some embodiments, thetransparent section is made from a glass. In some embodiments, thetransparent section further includes a suture.

In some embodiments, layer 3 has a thickness of about 100 nm to about1000 μm, preferably of about 100 μm to about 500 μm. In someembodiments, layer 3 includes a polymerizable and/or cross-linkablematerial that forms a nonresorbable material when polymerized and/orcross-linked. In some embodiments, layer 3 includes a catalystresponsive to UV light and configured to cause polymerization and/orcross-linking of the polymerizable and/or cross-linkable material oflayer 3. In one embodiment, the polymerizable and/or cross-linkablematerial includes methyl methacrylate (MMA) with a catalyst responsiveto visible or UV light.

In some embodiments, layer 3 includes a polymerizable amphiphilicmonomer. In some embodiments, the amphiphilic monomer includes acomponent selected from the group of branched or linear, substituted orunsubstituted, saturated or partially unsaturated C₁₀-C₃₀ alkyl-,alkenyl-, alkylaryl-, aryl-, cycloalkyl-, alkylcycloalkyl-,alkylcykloaryl-carboxylates, -phosphates, or -sulfates or mixturesthereof. In other embodiments, the amphiphilic monomer is at least onecomponent selected from the group of the linear unsubstituted C₁₀-C₂₀alkyl-carboxylates or alkyl-sulfates, or their alkali- or earthalkali-salts, respectively, preferably laurate, stearate, palmitate,myristate, oleate, behanate, dodecylsulfate, preferably as alkali- orearth alkali-salts or mixtures thereof. In some embodiments, layer 3includes epoxy resins, fibrin adhesive, polyurethane and combinationsthereof. In some embodiments, the polymerizable and/or cross-linkablematerial of layer 3 is a cyanoacrylate.

In some embodiments, as illustrated in FIG. 1, the layer 3 is protectedby a removable cover sheet 4 and the complete implant 1 is enclosed in asterile pack 5 prior to implantation. In some embodiments, cover sheet 4is preferably a multi-layer cover sheet. The multi-layer cover sheet maycomprise e.g., a thicker paper layer and a thinner anti-adhesion layerconfigured for direct contact with said layer 3 of polymerizable and/orcross-linkable material.

In some embodiments, sterile pack 5 is made from a radiation-blockingmaterial to prevent premature activation of the polymerizable and/orcross-linkable material. In some embodiments, sterile pack 5 is madefrom a material opaque to visible and/or UV-light. In some embodiments,sterile pack 5 is configured to isolate implant 1 from moisture.

In use, according to certain embodiments of the invention, implant 1 isremoved from sterile pack 5 and cover sheet 4 is removed to expose layer3. Implant 1 (e.g., in the form of a tack or other fixation element) ispushed through a plate hole of a bone plate positioned on a bone untilfront end 18 of implant 1 with the layer 3 of a polymerizable and/orcross-linkable material contacts the bone beneath the bone plate. Insome embodiments, a pressure is applied to implant 1 (e.g., on rear end19) to maintain contact between the bone and layer 3. In someembodiments, implant 1 makes contact with but does not penetrate throughthe surface of the bone. In some embodiments, implant 1 does notpenetrate into the cortical layer of the bone. In some embodiments,implant 1 penetrates into the bone no further than the cortical layer ofthe bone.

As described herein, implant 1 or a section thereof adjacent to frontend 18 in some embodiments is made from a transparent material. In someembodiments, by directing visible or UV light from a light source (e.g.,UV lamp or a dental curing lamp) through the transparent material ofimplant 1, layer 3 is activated and polymerizes and/or cross-links toadhere to the bone portion against which it has been pushed underpressure. In some embodiments, pressure may be applied to the implant 1by hand. In other embodiments, pressure may be applied by a lightguideof the lightsource (e.g., UV lamp). The combined effect of pressure withlight will ensure a good activation of the polymerizable and/orcross-linkable material of layer 3 and a good adhesion of implant 1 tothe bone. In some embodiments, pressure is maintained on implant 1 forsufficient time for substantially the entire layer 3 to polymerizeand/or cross-link. In some embodiments, layer 3 is configured topolymerize and/or cross-link in less than 5 minutes from activation. Insome embodiments, layer 3 is configured to polymerize and/or cross-linkin less than 1 minute from activation. In some embodiments, layer 3 isconfigured to polymerize and/or cross-link in about 30 seconds to about2 minutes after pressing implant 1 against the bone portion, preferablyin less than 1 minute. In some embodiments, layer 3 is configured topolymerize and/or cross-link in 30 seconds or less after pressing thetack against the bone portion. In some embodiments, layer 3 isconfigured to form chemical bonds the bone during polymerization and/orcross-linking, thereby adhering implant 1 to the bone. Adherence to thebone can be enhanced, according to some embodiments, by removing theperiost from the bone surface at the location where the tack is to bepositioned. In some embodiments, implant 1 is configured to adheredirectly to the bone surface. In some embodiments, the adhesion strengthof implant 1 to the bone is at least 10 MPa.

In some embodiments, a layer of primer material is first applied to thebone surface on which layer 3 is positioned. In some embodiments, theprimer material is selected to react with and bind to the bone surfaceand layer 3 during polymerization and/or cross-linking. In someembodiments, the primer material is configured to etch the mineralizedportion of the bone and penetrate into the bone surface. In someembodiments, the primer material is configured to chemically cross-linkwith amino acids and be capable of forming chemical bonds with organicparts (e.g., proteins) of the bone. In some embodiments, the primermaterial includes chemical groups (e.g., methacrylates) that arecross-linkable with the material of layer 3. Example primer materialsthat may be used in certain embodiments include acidic methacrylate ordimethacrylate monomers and 4-methacryloyloxyethyl trimellitateanhydride (4-META).

In a further embodiment, layer 3 of the polymerizable and/orcross-linkable material of the light activation type can be activatedjust before insertion of implant 1 into the plate hole of the bone plateby irradiating the polymerizable and/or cross-linkable material of layer3 with visible or UV light. In some embodiments, the light to activatethe polymerizable and/or cross-linkable material is supplied by a UVlamp, a dental curing lamp, or other light source known in the art. Thetack with the activated layer 3 can be then pressed through the plateopening and onto the surface of a bone.

The amount of light and duration of exposure used to activate layer 3 toinitiate polymerization and/or cross-linking, in some embodiments, canbe adjusted based on the amount of and type of monomer contained inlayer 3. In some embodiments, the activation time before insertion ofthe tack is less than 30 seconds, preferably about 5 seconds. In someembodiments, activation of the polymerizable and/or cross-linkablematerial can be achieved by exposure to light for about 5 seconds toabout 1 minute, preferably less than 1 minute. In some embodiments,activation of the polymerizable and/or cross-linkable material can beachieved by exposure to light for about 5 seconds to about 30 seconds.In some embodiments, exposure to light should not exceed 1 minute. Insome embodiments, activation of the polymerizable and/or cross-linkablematerial can be achieved by exposure to light for about 5 minutes. Inother embodiments, activation of the polymerizable and/or cross-linkablematerial can be achieved by exposure to light for less than 5 minutes.In some embodiments, the light intensity to activate the polymerizableand/or cross-linkable material is on the order of 1000 mW/cm².

In some embodiments, layer 3 includes a moisture-activated polymerizableand/or cross-linkable material. According to these embodiments, layer 3can be activated by exposing layer 3 to moisture prior to contacting thebone surface. In some embodiments, moisture-activated polymerizableand/or cross-linkable material is a moisture-activated isocyanate thatpolymerizes into a polyurethane.

In some embodiments front end 18 is substantially flat. In otherembodiments, front end 18 defines a concave surface. In someembodiments, front end 18 is contoured to substantially match thecurvature of the bone surface to be contacted. In some embodiments,front end 18 is made from a compliant material that can mold to thecontour of the bone surface when pressed against the bone surface. Insome embodiments, the compliant material can include a softened basematerial, silicone, or flexible biocompatible polymer material.

FIGS. 4 to 7 illustrate the use of an exemplary embodiment of theassembly including a plurality of fixation elements 9 according to FIGS.2 and 3 in combination with a bone plate 7 for the treatment of a baseproximal phalanx fracture. The bone plate 7 has several plate holes 8with an internal thread into which a fixation element 9 each can beinserted as illustrated in FIG. 4.

Commonly, hand fractures are treated with bone plates 7 either straightor T-shaped as illustrated in FIG. 4 that are fixed on the phalanx ormetacarpal with bone screws, providing a good stability. Accordingembodiments of the present invention, bone plate 7 can be attached tothe bone with fixation elements 9, e.g., the tacks according to FIGS. 2and 3. In some embodiments, fixation elements 9 are made of PMMA andhave their front side 11 coated with a layer 3 of a polymerizable and/orcross-linkable material. After removal of the periosteum and activationof the layer 3 as described herein, fixation element 9 is screwed into aplate hole 8 and forwarded as far as the front side 11 of the fixationelement 9 abuts on the bone surface. In some embodiments, at least partof the surfaces fixation element 9 and said plate hole 8 includeinterlocking means, for example, in the form of hooks and eyelets. Insome embodiments, fixation elements 9 are sized and dimensioned suchthat the rear ends 19 of each fixation element is substantially flushwith a top surface of bone plate 7 when fully screwed into plate holes 8as shown in FIG. 7. In some embodiments, fixation element 9 makescontact with but does not penetrate through the surface of the bone. Insome embodiments, fixation element 9 does not penetrate into thecortical layer of the bone. In some embodiments, fixation element 9penetrates into the bone no further than the cortical layer of the bone.

FIGS. 5 and 6 illustrate the bone plate 7 fixed to the proximal phalanxby means of the fixation elements 9 which are adhered on the surface ofthe proximal phalanx.

FIG. 8 illustrates another embodiment of the assembly wherein eachfixation element 9 is locked in the plate hole 8 by means of a cap 13.In some embodiments, cap 13 is configured to at least partially coverthe top of fixation element 9. In some embodiments, cap 13 is configuredto screw into the plate hole 8 on top of the fixation element 9. In someembodiments, cap 13 is configured to prevent exit of fixation element 9from hole 8. In some embodiments, cap 13 is configured to prevent softtissue ingrowth into hole 8. In some embodiments, cap 13 is configuredto receive a tool for screwing or driving cap 13 into bone plate 7. Insome embodiments, a surface of cap 13 defines a cavity for receiving thetool.

With reference now to FIG. 9, in some embodiments a method of thepresent invention includes first securing fixation element 9 to asurface of a bone 21. In some embodiments, fixation element 9 includes afront end coated with a layer of a polymerizable and/or cross-linkablematerial which is activated as described herein and contacted to thesurface of bone 21 to secure fixation element 9 to bone 21. For example,in some embodiments, the layer of polymerizable and/or cross-linkablematerial is activated by exposure to electromagnetic energy, light, ormoisture and then pressed against the surface of bone 21. Similar to theembodiments of FIGS. 1 to 3, the layer of polymerizable and/orcross-linkable material can be protected by a removable cover sheetwhich is removed prior to activation.

After securing fixation element 9 to the surface of bone 21, bone plate7 may then be coupled with fixation element 9. In some embodiments, boneplate 7 is coupled with fixation element 9 by positioning bone plate 7to receive fixation element 9 in hole 8 of bone plate 7 while fixationelement 9 is secured to bone 21. In some embodiments, fixation element 9is coupled with and secured to bone plate 7 (e.g., within hole 8) by aninterference, friction, or snap fit. In other embodiments, hole 8 isprovided with internal threads and fixation element 9 is configured tothread into hole 8 of bone plate 7.

In further embodiments, a cap 13 as described herein may be providedover hole 8 to cover an exposed end (e.g., rear end) of fixation element9. Cap 13 according to some embodiments may be configured to preventsoft tissue ingrowth into hole 8. In some embodiments, cap 13 is securedto bone plate 7 after bone plate 7 is coupled with fixation element 9.In some embodiments, cap 13 includes a threaded portion 13 a configuredto thread into hole 8 of bone plate 7 and a top portion 13 b having adiameter larger than the diameter of hole 8. In other embodiments, cap13 may be secured into hole 8 of bone plate 7 by an interference,friction, or snap fit.

FIG. 10 illustrates a further example of the use of the implant 1 in thecase of repositioning bone fragments 21 a; 21 b. The implant 1 accordingto this example is configured as a pin 17. Each pin 17 is affixed to abone fragment 21 a; 21 b. The pin 17 has a length L that is dimensionedso that, e.g., a reposition forceps can be positioned at the rearportion of one or each of the two pins 17. In some embodiments, pin 17has a length L of at least 40 mm. In some embodiments, pin 17 hasminimum length of about 45 mm to about 50 mm. In some embodiments, pin17 has a maximum length of about 100 mm to about 110 mm.

The pin 17 comprises a longitudinal axis 23, a front end 18 with a frontside 11, a rear end 19 and a section 2 which, in some embodiments, ismade of a rigid material and which includes a layer 3 of a polymerizableand/or cross-linkable material as described herein. The section 2 canextend from the rear end 19 to the front end 18 of said pin 17 so thatsaid layer 3 of a polymerizable and/or cross-linkable material islocated at the front side 11 of the pin 17. When said pin 17 isimplanted into the human or animal body said layer 3 can contact thesurface of a bone. In some embodiments, pin 17 makes contact with butdoes not penetrate through the surface of the bone. In some embodiments,pin 17 does not penetrate into the cortical layer of the bone. In someembodiments, pin 17 penetrates into the bone no further than thecortical layer of the bone.

In some embodiments, pin 17 can be made of a biocompatible and biostablepolymer, preferably of polyether ether ketone (PEEK) or PMMA. The layer3 can be made of a polymerizable and/or cross-linkable material,preferably MMA with a catalyst responsive to visible or UV light.Alternatively, the layer 3 of a polymerizable and/or cross-linkablematerial can be made of a moisture-activated isocyanate leading to apolyurethane so that the layer 3 of a polymerizable and/orcross-linkable material can be activated with moisture.

Similarly to the embodiments of FIGS. 1 to 3 the layer 3 can beprotected by a removable cover sheet and the complete implant 1 can beenclosed in a sterile pack. In use, pin 17 is removed from the sterilepack and the cover sheet, when present, is removed. Pin 17 issubsequently pushed through the soft tissue until the front side 11 ofthe pin 17 with the layer 3 of a polymerizable and/or cross-linkablematerial attached thereto contacts the bone.

In some embodiments, layer 3 of a polymerizable and/or cross-linkablematerial can be activated just before insertion into the soft tissue,and the pin 17 with activated layer 3 can be pushed through the softtissue until the front side 11 of the pin 17 with the layer 3 of apolymerizable and/or cross-linkable material attached thereto contactsthe bone. In some embodiments, layer 3 includes a light-activatedpolymerizable and/or cross-linkable material and can be activated byexposure to light just before insertion into the soft tissue. Inalternative embodiments, layer 3 includes a moisture-activatedpolymerizable and/or cross-linkable material (e.g., a moisture-activatedisocyanate leading to a polyurethane) and can be activated with moisturejust before insertion into the soft tissue.

Furthermore as shown in FIG. 10, according to some embodiments, areposition instrument 14 in the form of a distractor or tractioninstrument or an external fixator can be attached to the two pins 17. Insome embodiments, the reposition instrument 14 can include a threadedconnector rod 15 and a clamping device 16 each for coupling thereposition instrument 14 to the pins 17. A nut 22 which is laterallyscrewed onto the threaded connector rod 15 is configured to push the twobone fragments 21 a; 21 b towards each other. A second nut is screwedonto the threaded connector rod 15 between the two pins 17 so that thetwo bone fragments 21 a; 21 b can be distracted when required.Alternatively, in other embodiments, a universal chuck with a T-handlecan be fixed to each pin 17 for manually reducing the bone fracture. Insome embodiments, after repositioning the bone fragments 21 a; 21 b thereposition instrument 14 can be removed and an internal or externalfixator can be affixed to the pins 17.

After the bone fracture has healed, pins 17 may be removed from the bonesurface according to some embodiments through mechanical forcesufficient to break the bond between layer 3 and the bone surface. Insome embodiments, the bone surface where pins 17 were attached may becleaned to remove any residual polymer material. In some embodiments,removal of pins 17 will not leave cavities in the bone because pins 17did not penetrate into the surface of the bone.

Although the invention and its advantages have been described in detail,it should be understood that various changes, substitutions, andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, andcomposition of matter, means, methods and steps described in thespecification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, composition of matter, means, methods, or steps,presently existing or later to be developed that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention.

It will be appreciated by those skilled in the art that variousmodifications and alterations of the invention can be made withoutdeparting from the broad scope of the appended claims. Some of thesehave been discussed above and others will be apparent to those skilledin the art.

The invention claimed is:
 1. An assembly for implantation in a patientcomprising: an implant comprising: a rear end for manipulating theimplant; a front end comprising an uncured layer of a polymerizableand/or cross-linkable material, the uncured layer being configured tocontact a surface of a bone and adhere the implant to the surface of thebone, wherein the front end is substantially flat and does not includean opening; a cylindrical core extending from the rear end of theimplant to the front end of the implant; a section of said cylindricalcore made of a rigid transparent polymer adjacent to the front endconfigured to transmit visible and/or UV light from the rear end of theimplant to the front end of the implant; and a bone plate comprising aplurality of plate holes, each plate hole having an internal thread,wherein said implant is a fixation element for attaching the bone plateto the bone without the implant penetrating further than a corticallayer of the bone, the fixation element including a rear side at saidrear end, one or more lateral sides, a front side at said front end forinsertion into one of said plate holes, and an external thread on thecylindrical core extending from said rear side to said front side forengaging with the internal thread of said one of said plate holes, saidfront side being provided with said uncured layer of the polymerizableand/or cross-linkable material, wherein the assembly is configured to beattached to the bone without the bone being penetrated further than thecortical layer of the bone.
 2. The assembly according to claim 1,wherein said uncured layer comprises a polymerizable amphiphilic monomeron an outer surface of the implant.
 3. The assembly according to claim2, wherein said amphiphilic monomer comprises a component selected fromthe group consisting of branched or linear, substituted orunsubstituted, saturated or partially unsaturated C₁₀-C₃₀ alkyl-,alkenyl-, alkylaryl-, aryl-, cycloalkyl-, alkylcycloalkyl,alkylcykloaryl-carboxylates, -phosphates, or -sulfates, and mixturesthereof.
 4. The assembly according to claim 2, wherein said amphiphilicmonomer includes at least one component selected from the groupconsisting of the linear unsubstituted C₁₀-C₂₀ alkyl-carboxylates oralkyl-sulfates, or their alkali- or earth alkali-salts, respectively. 5.The assembly according to claim 2, wherein said amphiphilic monomerincludes at least one component selected from the group consisting oflaurate, stearate, palmitate, myristate, oleate, behanate,dodecylsulfate, their alkali- or earth alkali-salts, and mixturesthereof.
 6. The assembly according to claim 1, wherein saidpolymerizable and/or cross-linkable material is a moisture-activatedisocyanate capable of forming a polyurethane.
 7. The assembly accordingto claim 1, wherein said implant is configured as a tack, pin, screw, orbolt.
 8. The assembly according to claim 1, wherein said uncured layeris protected by a removable cover comprising multiple layers, themultiple layers including an anti-adhesion layer in contact with theuncured layer of the polymerizable and/or cross-linkable material. 9.The assembly according to claim 1, wherein said transparent polymersection is transparent to UV irradiation.
 10. The assembly according toclaim 1, wherein said uncured layer comprises a material chosen from thefollowing group: epoxy resins, fibrin adhesive, polyurethane andcombinations thereof.
 11. The assembly according to claim 1, whereinsaid uncured layer has a thickness of 100 nm to 1000 μm.
 12. Theassembly according to claim 1, wherein said polymerizable and/orcross-linkable material is a cyanoacrylate.
 13. The assembly accordingto claim 1, wherein said one or more lateral sides are provided at leastpartially with said layer of a polymerizable and/or cross-linkablematerial.
 14. The assembly according to claim 1, wherein at least partof the threads of said fixation element and of said plate holes areconfigured to interlock.
 15. The assembly according to claim 1, whereinthe polymerizable and/or cross-linkable material forms a nonresorbablematerial when polymerized and/or cross-linked.
 16. The assemblyaccording to claim 1, wherein the implant is configured to not penetratethrough the surface of the bone during implantation.
 17. The assembly ofclaim 1, wherein the rear end and the front end of the implant have thesubstantially same diameter.
 18. An implant for implantation in apatient comprising: a rear end for manipulating the implant; a front endcomprising an uncured layer of a polymerizable and/or cross-linkablematerial, the uncured layer being configured to contact a surface of abone and adhere the implant to the surface of the bone, wherein thefront end is substantially flat and does not include an opening; acylindrical core extending from the rear end to the front end; a sectionof said cylindrical core made of a rigid transparent polymer adjacent tothe front end, wherein said rigid transparent polymer section isconfigured to transmit visible and/or UV light from the rear end of theimplant to the front end of the implant; and an external thread on thecylindrical core extending from the rear end to the front end, whereinthe implant is provided with a removable cover comprising multiplelayers adjacent to the front end, the multiple layers comprising ananti-adhesion layer in contact with the uncured layer of thepolymerizable and/or cross-linkable material.
 19. An assemblycomprising: the implant according to claim 18; and a bone platecomprising a plurality of plate holes, each plate hole having aninternal thread for engaging with the external thread of the implant,wherein said implant is a fixation element with a rear side at said rearend, one or more lateral sides, and a front side at said front end forinsertion into one of said plate holes, said front side being providedwith said uncured layer of the polymerizable and/or cross-linkablematerial, wherein the assembly is configured to be attached to the bonewithout the bone being penetrated further than a cortical layer of thebone.
 20. The implant according to claim 18, wherein the implant isconfigured to penetrate into the surface of the bone no further than acortical layer of the bone.
 21. An assembly for attachment to a surfaceof a bone comprising: an implant having a top surface, a bottom surfaceopposite the top surface, and at least one hole extending through theimplant from the top surface to the bottom surface, the at least onehole being externally bounded by an inner wall; and a fixation elementcomprising: a front end having a layer comprising polymerizable and/orcross-linkable material that is adherent to the surface of the bone whenthe polymerizable and/or cross-linkable material is activated, whereinthe front end is substantially flat and does not include an opening; arear end opposite the front end, the rear end configured to receive atool for driving the fixation element into the at least one hole of theimplant; a cylindrical core extending from the rear end of the implantto the front end of the implant; a rigid transparent section of saidcylindrical core positioned between the front end and the rear end, therigid transparent section configured to transmit visible and/or UV lightto the layer of polymerizable and/or cross-linkable material; and asidewall of the cylindrical core extending from the front end to therear end, the sidewall being configured to engage the inner wall of theimplant, the sidewall comprising an external thread extending from therear end to the front end that is configured to engage with the innerwall of the implant, wherein the assembly is configured to be attachedto the bone without the bone being penetrated further than a corticallayer of the bone.
 22. The assembly of claim 21, wherein the rear endcomprises a cavity for receiving the tool.
 23. The assembly of claim 21,wherein the transparent section extends from the front end to the rearend.
 24. The assembly of claim 21, wherein the front end furthercomprises a compliant material configured to bend to match a contour ofthe surface of the bone.
 25. The assembly of claim 21, wherein theassembly is configured to be attached to the bone without the use ofbone screws.